Among rare-earth magnets, an R-T-B system rare earth permanent magnet has been used in various electric appliances such as speakers and motors because magnetic properties thereof is excellent, and a main component thereof, Nd, is abundant as a natural resource and relatively inexpensive.
However, in these years, demand for downsizing of electric devices and machines has grown markedly, and accordingly development of new permanent magnet materials has been advanced.
Among such materials are rare earth-iron system magnet materials, having a body-centered tetragonal structure or a ThMn12-type structure, reported in, for example, Japanese Patent Laid-Open Nos. 63-273303, 4-241402, 5-65603 and 2000-114017.
Japanese Patent Laid-Open No. 63-273303 discloses a rare earth permanent magnet represented by a formula, RxTiyAzFeaCob (in this formula, R is one of the rare earth elements inclusive of Y; A is one or more of B, C, Al, Si, P, Ga, Ge, Sn, S and N; and x is 12 to 30% by weight, y is 4 to 10% by weight, z is 0.1 to 8% by weight, a is 55 to 85% by weight, and b is 34% or less by weight, respectively). Japanese Patent Laid-Open No. 63-273303 describes that the element A intervenes between atoms to modify the Fe—Fe distances along preferable directions.
Japanese Patent Laid-Open No. 4-241402 discloses a permanent magnet represented by a formula, RxMyAzFe100-x-y-z (in this formula, R is at least one element selected from rare earth elements inclusive of Y; M is at least one element selected from Si, Cr, V, Mo, W, Ti, Zr, Hf and Al; A is at least one element selected from N and C; and x is 4 to 20% by atom, y is 20% or less by atom, and z is 0.001 to 16% by atom), this permanent magnet having as the main phase thereof a phase having a ThMn12-type structure. Additionally, Japanese Patent Laid-Open No. 4-241402 discloses that a rare earth-iron system tetragonal compound having a stable ThMn12-type structure can be formed by adding the element M (Si, Ti and the like); and Japanese Patent Laid-Open No. 4-241402 discloses that the element A (C, N) is effective for improving the Curie temperature.
Japanese Patent Laid-Open No. 5-65603 discloses an iron-rare earth system permanent magnet material comprising R: 3 to 30% by atom, X: 0.3 to 50% by atom and the balance substantially composed of Fe where R is one element or a combination of two or more elements selected from the group consisting of Y, Th and all the lanthanoid elements, and X is one of or a combination of the elements N (nitrogen), B (boron) and C (carbon), this permanent magnet material having as the main phase thereof a phase having a body-centered tetragonal structure. Japanese Patent Laid-Open No. 5-65603 further proposes that the magnet material includes M: 0.5 to 30% by atom by partially replacing Fe with the element M (one element or a combination of two or more elements selected from the group consisting of Ti, Cr, V, Zr, Nb, Al, Mo, Mn, Hf, Ta, W, Mg, Si, Sn, Ge and Ga). In Japanese Patent Laid-Open No. 5-65603, the element M is regarded as an element having a significant effect in generating the body-centered tetragonal structure.
Additionally, Japanese Patent Laid-Open No. 2000-114017 discloses a permanent magnet material represented by a general formula (R1-uMu) (Fe1-v-wCovTw)xAy (in this formula, R, M, T and A are respectively R: at least one element selected from rare earth elements inclusive of Y, M: at least one element selected from Ti and Nb, T: at least one element selected from Ni, Cu, Sn, V, Ta, Cr, Mo, W and Mn, A: at least one element selected from Si, Ge, Al and Ga; and u, v, w, x and y are respectively such that 0.1≦u≦0.7, 0≦v≦0.8, 0≦w≦0.1, 5≦x≦12, and 0.1≦y≦1.5). This permanent magnet material has as the main hard magnetic phase there of a ThMn12-type structure. Japanese Patent Laid-Open No. 2000-114017 describes that substitution of the element R with the element M makes it possible to reduce the contents of Si, Ge and the like which are the elements to stabilize the phase having the ThM12-type structure (hereinafter referred to as “ThM12 phase” as the case may be).
Rare earth permanent magnets are required to have high magnetic properties and on the other hand also to be low in cost. Among the rare earth elements constituting the rare earth permanent magnet, Nd is lower in price than Sm, and hence it is preferable that Nd, inexpensive compared to expensive Sm, makes the main component of the rare earth elements. However, the use of Nd makes the generation of the ThMn12 phase difficult, so that the production of the magnet concerned requires a long time heat treatment at a high temperature. More specifically, for example, annealing has been made at 900° C. for 7 days in the above described Japanese Patent Laid-Open No. 5-65603, and only Sm has been used as the rare earth element except for some exceptions in Japanese Patent Laid-Open Nos. 4-241402 and 2000-114017.
In view of the above circumstances, the present invention takes as its object the provision of a hard magnetic compound capable of easily generating the ThMn12 phase even when Nd is used as a rare earth element, a permanent magnet powder and the like.